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Generators & Electric Motors General Discussion Antique Generators and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Electric Motors General Discussion

Best Tuning for Old Generators question


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  #1  
Old 10-23-2018, 10:13:50 AM
JohnFM JohnFM is offline
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Default Best Tuning for Old Generators question

A lot of us have old generators that we will use on occasion for what they were made for. That is to provide some electricity at times. I've run mine at times to provide some lights when the power goes out.

I've never been too fussy about adjustment, just setting the governor to give me enough AV volts for good bright lights. Then I discovered these forums and besides generators, found I have lots of interesting stuff in my boneyard.

About generators though, is the best route to tune for correct HZ or voltage ?
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Old 10-23-2018, 11:14:25 AM
Newoldstock Newoldstock is offline
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Default Re: Best tuning for old generators question

Ideally you want to be in the 3% range as as specified by the electrical code ( code suggested a total variation of 5% in branches and feeders added up ).
But often with these older sets your going to see swings in between 110 to as much as 130 volts no load.
The good news is most electrical equipment will tolerate this, electronics however might not.

Frequency goes hand in and hand with voltage.
You would like to be between 58 and 62, but often these sets can't do that.
Lucky for us most electrical equipment would prefer a drop in frequency with voltage as well as an increase.
This keeps the magnetic parts from saturating or thinning out too much so we can maintain the torque on a motor for example.

Old generators were not built with modern electronics in mind and you have to always remember this.
Higher end larger machines will do a better job, smaller cheaper machines will not.

I have a little Kohler plant I am really fond of.
Its good for the deep freeze or sump, pump florescent lights
I have a larger Onan that has a much more sophisticated regulation system and an excellent governor.
That one is the one I trust with electronics.
So think about what you are asking from your machines.

Your generators may have sensitivity adjustments.
These are a good place to start.
Ideally you want to make them as sensitive as possible without causing hunting.
Hunting is a low frequency oscillation caused by excessive feedback in a control system.
This should not be confused with hunting caused by a fuel system issue.
In this case the governor is too sensitive and overshoots the set point of 60hz and then over reacts and undershoots 60 again as the throttle closes.
You may find the engine is most likely to hunt at low load but stable at high load.
This is the limit of your governed to adjust for different loads and you will need to move your governor spring further down the arm away from the centre of the pivot point to make it less sensitive.

Voltage adjustments if you have them.
Set your generator for the highest tolerable voltage this should be around 125 volts, but some generators may be set higher to compensate for line loses. ( but going much higher is bad )

Some places like my own home have power from the utility that fluctuates.
I use a power conditioner to protect my PC.
You should too if you have expensive electronics.
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Old 10-23-2018, 12:13:10 PM
Fred M. Fred M. is offline
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Default Re: Best tuning for old generators question

Quote:
Originally Posted by JohnFM View Post
About generators though, is the best route to tune for correct HZ or voltage ?
John-

I agree with Newoldstock, but I think Hz is more critical.

Try setting it for 62 Hz no load. Voltage should be at least 120, perhaps as high as 130. Then with a moderate load, frequency should be around 60 Hz and voltage at least 110.

If your generator can't maintain this, then repair is needed.

Fred
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Old 10-23-2018, 12:29:16 PM
JohnFM JohnFM is offline
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Default Re: Best tuning for old generators question

Thanks for the info provided so far.
My old genset is rated for 115 volts at 1800 RPM.
When I need to run it I usually have set to around 120 volts to get good light from standard bulbs. It'll hold steady at a couple tenths of a volt.
I never ran across a meter I could read HZ with locally, so I ordered a Killavolt which I should have in a few days. Curiosity led me to this more than anything else. I'll be interesting to see how it does holding 60 HZ and what sort of voltage it has. Good idea about setting no load HZ to about 62 and then seeing what it does with various loads.

All my modern electronics, computers, TV, ya da are protected by UPS, conditioners, etc.
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Old 10-23-2018, 12:57:12 PM
Newoldstock Newoldstock is offline
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Default Re: Best Tuning for Old Generators question

Voltage creep is another modern issue.

Walking from one end of the plant I work in to another is like a trip through time.
In some places its the 1930s and I see electrical equipment marked 550 volt or 2200 volt ( and they mention if its 60 hz because we had some 25 cycle too ).
Walk into equipment built in the 60s and 70s I see 575 and 4160 more often ( sometimes 6900 )
Modern stuff is 600 volt and 13.8 kv.

Voltages have gone up to reduce line losses and branch circuit creep has raised the voltage levels to 600 from 550.
Even in my own home I see 110 and 220 being replaced by 120 and 240.

Your old set however was might have been built on the assumption of 110 for ever......
Good news is most electrical equipment will tolerate larger swings of voltage than we are told and most prefer it higher than lower.
Just remember to have a good power condition and surge suppressor to protect electronics.
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Old 10-23-2018, 02:12:41 PM
JohnFM JohnFM is offline
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Default Re: Best Tuning for Old Generators question

I'll never do more than run a 10 gauge extension cord over to the house. Not big enough to run fridge, freezer, water pump, etc. anyway; to get too fancy.
After enough tests, since all the spendy electronics are on their own circuit, I'll test that load and see how it does, plus some lights.
Also be nice to be able to run the O2 machine I need at night now if it looks like a night without power. The old thing always runs 12 hours plus at a light load on a tank of gas.
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Old 10-23-2018, 09:14:05 PM
Vanman Vanman is offline
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Default Re: Best Tuning for Old Generators question

I like to set them at 115 volt and 60 cycle at half load. I like limits of 105 to 125. I set the governor as sensitive as possible without hunting when warmed up.
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Old 10-24-2018, 08:22:09 AM
JohnFM JohnFM is offline
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Default Re: Best Tuning for Old Generators question

Yes, I have a heater I use to apply a half load.
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Old 10-24-2018, 06:56:04 PM
Railroads Railroads is offline
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Default Re: Best Tuning for Old Generators question

Setting for correct HZ is more critical. On old Coleman generators they might be as high as 140 volts no load at 62/63HZ.

Robert
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Old 10-25-2018, 07:56:39 PM
JohnFM JohnFM is offline
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Default Re: Best Tuning for Old Generators question

I got that Killawatt tester today and used it to set up the old genset.
I ended up using 400 watts as a load to work with. Got the voltage holding at ~120 and HZ at ~60.
One thing I can't get is much response from the governor, but another fellow from the forums sent me some photos of one he has just like mine, but basically never run.
A good pic of the governor hook up shows a different spring than I have.
Tomorrow I'll fool around with some tension adjusting and see if I can get it to respond better to load changes.
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